Signal generation apparatus



C. L. ELLIS ETAL SIGNAL GENERATION APPARATUS by m S Mm Th ehr` Att OPHey.

New 24, 1953 NOV 24, 1953 c. L. ELLIS ETAL 6699,61

SIGNAL GENERATION APPARATUS Filed April ll, 1951 3 Sheets-Sheet 2 Hdl-1Inventors: CalvinA L. ls, Ralph W. Elsner,

b5 mm Y Their AttOT-Teg.

Nov. 24, 1953 c. L. ELLIS ET AL SIGNAL GENERATION APPARATUS 3Sheets-Sheet 5 Filed April 11, 1951 Patented Nov. 24, 1953 SIGNALGENERATION APPARATUS Calvin L. Ellis, Clay, N. Y., and Ralph W. Elsner,Phoenix, Ariz., assignors Vto General Electric Company,

a corporation ci New York Application April l1, i951, Serial No. 220,414

7 Claims.

The present invention relates, in general, to the production ofelectrical signals and more particularly to apparatus for developinghorizontai and vertical synchronizing and equalizing signals fortelevision apparatus.

In television transmission systems electron beam type devices are usedat the transmitter end and at the receiver end oi the system for thescansion of the image to he `televised and for its reproduction,respectively. In order to obtain a satisfactory reproduction of thetelevised image, it is essential that the horizontal and vertical motionof the electron beam at the receiver ce accurately synchronized with themotion of the electron beam at the transmitter. To this end asynchronizing signal comprising horizontal synchronizing, verticalsynchronizing and equalizing signals are sent with the picturecomponents of the television transmission.

According to present-day standards, the horizontal synchronizing signalcomprises pulses periodically recurrent at a rate of 15,750 cycles persecond. The vertical synchronizing signal comprises a group of sixpulses periodically re.- current at a rate of 60 cycles per second. Theequalizing signal comprises a group of twelve pulses, six immediatelypreceding a group of vertical pulses and six pulses immediatelyfollowing the vertical pulses, periodically recurrent at a rate of 60cycles per second.

ln order to obtain proper operation of the receiving apparatus it isessential for the syn chronizing pulses and .the equalizing pulses to beaccurately controlled in duration and time of occurrence. To this end ithas been proposed to generate all or" the above three components of thesynchronizing signal .from a single generator, for example, from asingle relaxation type oscillator having two stable states ofequilibrium. Suitable triggering or actuating pulses are ap plied to thegenerator to switch from one stable state to the other and back, therebydeveloping current pulses in the output circuit of the generator ofaccurately controlled time of occur rence and duration.

ince the duration and periodicity of the horizontal synchronizing, thevertical synchronizing the equalizing pulses are different, it is necessary to apply diilerent triggering pulses to the aforementionedgenerator `to develop dilerent components of the complete synchronizingsignal. The present invention is particularly, though not exclusively,addressed to the problem of generation of signals generally termed inthe art as gating signals to control `the application of theabove-referred-to triggering pulses to the aforementioned synchronizingsignal generator.

It is an object of the present invention to pro vide improvements insynchronizing signal generation apparatus.

lt is another object of the present invention to provide improvements inapparatus for developing synchronizing signals which are in accuratetime relationship to one another.

It is still another object or" the present invention to provide reliableand versatile apparatus for the generation of accurately timed gatingpulses for particular use in synchronizing signal generation.

It is a further object of the present invention to provide simple yeteiective and reliable apparatus requiring a minimum of adjustments for Xdeveloping pulses of accurately controlled duration and occurrence.

It is a general object of the present invention to provide improvementsin signal generation apu paratus.

The novel features which We believe to he characteristic of ourinvention are set forth With particuiarity in the appended claims. Ourinvention itself, however, both as to its organization and method oioperation, together with further objects and advantages thereof, may beunderstood by reference to the following descrip tion taken inconnection with the accompanying drawings in which Fig. l shows adiagram of a standard television signal showing the duration and time ofoccurrence of the horizontal synH chronizing, the vertical synchronizingand the equalizing pulses; Fig. 2 is a block or line diagram showing ourinvention; Fig. 3 is a diagram of Wave forms useful in explaining ourinvention; Fig. l is a schematic diagram of a portion ci the cir cuitsshown the block diagram of Fig. 2.

Referring now to Fig. 1, there is shown a portion of a standardtelevision signal ci the kind which modulates the television transmitterand which is detected by a television receiver. The pulses labeledhorizontal synchronizing pulses function to synchronize the horizontalmotion of the beam of the cathode ray tube at the receiver with theelectron beam of the iconos-cope or some other similar camera device atthe transmitter station. The group of pulses labeled 'erticalsynchronizing pulse functions to maintain the vertical motion of theelectron heain at the receiver in synchronism with the vertical motionelectron beam at the transmitter station. The

" group of pulses labeled eoualizing pulses function to provide atransition region between vertical synchronizing pulses and thehorizontal synchronizing pulses so that the horizontal synchronizing andvertical synchronizing pulses can be effectively segregated at thereceiver to perform their above-referred-to functions.

For proper operation of television systems it is essential that theduration and time of occurrence of each of the aforementioned groups ofpulses be accurately controlled. The provision of ap paratus to achievethis objective is a particular object of the present invention.

The portion of the signal labeled horizontal blanking functions tonullify the effect .of the electron beam of the cathode ray tube `on thescreen thereof during the return of the beam after a horizontalscansion. YThe portion of the signal labeled vertical blanking functionsto nullify the effect of the electron beam of the cathode ray tube onthe screen thereof during the return of the beam after a verticalscansion. The portion of the signal labeled video represents variationsin intensity and functions to produce variations in light intensity onthe screen `of the cathode rayv tube during the horizontal zscansion ofthe electron beam. The aggregate effect of the variations in lightintensity produced on the screen due to the'progressive and periodiclscansion by'the electron beam is a television picture.

Referring now to Fig. 2, there is shown vapparatus in block form for thegeneration of the horizontal synchronizing, 'vertical synchronizing andequalizing pulses referred to above. This apparatus comprises a delayline I having an input terminal 2 and output terminals 3, 4, 5, 5 and'I.. The signals ,applied to 'terminal 2 may be recovered at the outputcontacts of the delay line; however, they Will'be delayed in time bypredetermined intervals. Contact 3 .of the delai7 line is. connected tovtheinput .circuitof ampliner 8,.the output circuitof Whichisconnectedto the input circuit of counter 9. Counter 8 .develops in its outputcircuit an .impulseor every lsix pulses applied to its input circuit.The output circuit or counter v9 is connected to .the input circuit ofcounter amplifier I0. The output circuit of counter amplier lis.connectedto both the input circuit of counter II and the input circuitof counter I2.

Counter II is a heavily biased relaxation 4type oscillator which has twostable conductive states. Application of pulses to the input circuit ofthe counter I I will cause the counter to change from one conductivestate to another. a device which functions to develop in the outputcircuit a single impulse for every three pulses applied to its inputcircuit. vThe output circuit of counter I2 is connected to theinputcircuit of counter I3. Counter I3 is :aheavily biased relaxation typeoscillator .having ytwostable .con- Yductive states. .Application .ofpulsestothe input `circuit of counter .I3 will causethe counter tochange from one statepf equilibriumto -thefother state of equilibrium.

The output circuit .of "counter .I3 is .connected to the .input circuitof amplifier .I4. The output circuit of the amplifier Ulis connected to:a :cur- Vrent control electrode on amplifier 8. The connection from theoutput circuit of ampliner I4 to the current control electrode ofampliiier V8 is arranged so that only during a particular conductivestate of counter I3 does amplifier 8 pass .signals which are .applied toits input circuit.

The input circuits Yof counter yII and .counter `I3 Counter I2 isgraphs.

are also connected to the output circuit of amplifier I5, to the inputcircuit of which may be applied a periodic pulse signal.

The operation of the circuit combination of Fig. 2 described above willbe understood by rcferring to Fig. 3 Where are shown graphs of signalsappearing` at various points in the circuits .of Fig..2. Signals havingthe waveforms shown in the graphs appear at points in the circuit ofFig. 2 having the same literal designation as the The abscissas of thegraphs represent .time and the vordinates of the graphs representvoltage amplitude of the signals. Short pulses .of twice horizontal linescanning frequency es shovvnin graph A are applied at terminal 2 ofdelay line I from a suitable source. Tfulses ap- 'nearing at terminal 3are slightly delayed in time by delay line I as is apparent by referringto graph B. These pulses are applied to the input of amplifier 8. Apulse corresponding to the leading edge of the `vertical bla king signalis simultaneously applied to the input circuit of arnplider I5 as shownin graph C. Since the output circuit of amplier I5 is connected to theinput circuit of counters Il and I3, counter II is caused to change fromone conductive state to another, as illustrated in graph D. Likewise,counter I3 is caused to change from one con'- ductive state to anotheras shown in graph E. The change in conductive state of counter I3 isapplied through amplifier Ill to the current control electrode ofamplifier 8 causing the latter to pass the aforementioned pulses appliedto its input circuit to the output circuit thereof.

After the occurrence of six pulses, counter 9 supplies a pulse throughthe counter amplifier lil to the counter Il causing the latter to again.change its conductive state as shown in graph D. After the passage ofsix more pulses through the amplier 8, the counter 9 again executes acornplete cycle and supplies another pulse to the counter II causing itto again change its con -ductve state, as shown in graph D. After the-passage of .a third group or six pulses through the ampliiier .8, the.counter 9 again executes a complete cycle ane. supplies a pulse to thecounter I I causingit again to change its conductive state` asshown in,graph D.

The eighteen pulses passed through amplifier B cause the appearance ofthree pulses at the output circuit of counter S which are supplied tocounter I2 causing the latter to execute a coinplete cycle and supply asingle pulse to the counter I3 which again changes its conductive stateas shown in graph E. This latter change is applied through arnpliner i4to the bias electrode ofamplier 8 to block passage of further pulsestherethrough until the next cycle of operation of the counter chaininitiated by the pulse applied to amplifier I5. y

Thus, it is seen that from the output circuit of `counter i i isobtained a signal having a waveform of the kind shown in graph 'D andfrom the outpu.l circuit'of counter i3 a signal having the Waveformofthe kind shown in graph E is obtained.

The signals represented by graphs D and .maybe combined. The signal ofgraph D is applied through arnpliier I6 to one control electrode ofmixer device I1. The signal of graph E is applied to another controlelectrode ci mixer device I1. From the output circuit of mixer de viceIl .is obtained a signal having waveform `shown .in graph F. The signalsrepresented by graphs D, and F are used in va manflbg.

ner to be described below in the generation of the horizontalsynchronizing, the vertical syn ohronizing and the equalizing pulses.

When A. C. coupling uset; between counter and il, a given conductivecondition coun., 5S will not always coincide with the biasing orunbiasinf; oi amplifier t which is required. for the proper operation ofthe counter chain described above. To assure this result, a positivecorresponding to the trailing erige of the vertical blanling pulse isapplied, through it to the binary counter i3 so that in operation of thecounter chain counter i3 always starts from a predetermined condition ofoperation Cont g now with the description oi the circuit of. terminal iof delay line l is connected the input circuit of amplifier l. Theoutput circuit of ainplier le is connected to the terminal 2l? ofsynchronizing signal -Y Generator 2i may a relaxation.. having tivostable eoneluctive pe generator is referred to in stable multivibrator.Terminal i is connected to the input circuit The output circuit ofainplier to stop terminal it oi multi-n lerfninal il of delay line i iected to the ut circuit of amo-li 'ier the output circuit of which isconnes rof generator 2i. ected to the input circuit of ainnl'er outputcircuit oi which is connecteti t erininal or" generator 2i.

The application of a pulse to start terminal oi generator causes currentconduction in the output circuit thereof and. on the application of a 1to stop terminal 23, the current eonauction ceases. Thus, the time ofoccurrence oi pulse ci current in the output circuit of the multii ratorSii may he controlled by the time of occurrence of pulses applied toterminal The duration of the pulse of current con trolleel the intervalbetween the pulses apm niieol to the start terminal 2@ and stop ternruinal The pulses to the generator 2l from terminal of delay line i areof twice horizontal line sean: frequency. Accordingly, the pulsesoetelopeu the output circuit of multivibrator are of t ice linefrequency.

he t :cuit of amplier it connected a int on ainplier 2t whereby antonina?. Terminal l of delay line l plier .l ioiered non-conductive duringthe interval ntel by the signal of graph E.

The output circuit of miser device il is connected to a nh-ase inverterstage 26. The output circuit oi the inverter connected. to a'biaselectrode on amplifier permitting the amplifier to he conductive onlyduring the occurrence the signal represented hy graph F. Amplifier le isconnected to a control point on amplifier 22 whereby aniplier isrendered conductive only during the ocean-rence of the positive portionsof the signal represented by graph D.

pulses oi twice horizontal line scanning ireare applied through amplierill t poin of multivibrator to establish in the outpu circuit or multiv"ator 2i the leading edges o oi twice e frequency. Since amplier isconductive all the time except for a period represented by substantiallynine successive hori zontal scanning lines corresponding to the width oithe pulse obtained from amplifier ifi, trailing edges of the pulses fromthe multivibrator El are establisheci by these pulses, except duringthis 9H interval, 9H referring to an interval substantially ninehorizontal scanning lines in duram tion. The width of the pulses oi thisfirst group has the Width of the horizontal synchronizing pulses of thesynchronizing signal.

Since amplifier 2e is conductive only the interval corresponding tosuhstantial horizontal scanning lines represerftso1 Toy the signal ingraph F, the trailing oi a seconti group of pulses centrally located inthe above referred to 9H interval and having a duration corresponding tothe delay between terminal and terminal 'l of delay line i, isestablished. This group oi pulses constitutes the vertical ehronizingsignal.

Since amplifier 22 is conductive Flur-ine the rf mainaer of the 9Hinterval, the traili u edges of this third group of pulses areestablished by triggering pulses obtained through this amplifier. TheWidth of this group of pulses corresponiis to the delay betweenterminals and o the delay line. latter of corresponds to the equalizingpulses oi the synclnonizw ing signal. l't thus seen that at the outputterminal of multivibrator 2i a signal having waveform of the kind showngraph G is obtained.

The output from the multivibrator 2i is applied to a gating amplifier 2.A signal having a Waveform oi the kind shown in graph l-I is alsoapplied to amplier 2l. The signal of the Waveform shown in graph I isobtained from the output circuit of the ainplier 2l. Ainplier 2l thusiunctions to delete alternate horizontal synchronizing pulses andthereby forni the complete synchronizing signal.

The waveform I is combined with horizontal and' vertical blankingsignals to obtain the complete television signal without the video comFponent as shown in graph J.

Referring 110W to Fig. 4, there is shown a schematic diagram of aportion of the apparatus shown in the block diagram of Fig 2. Referringnow particularly to the upper portion of this drawing, there is shown acounter chain coinprising elements 2S, 29, 3b, ii, 32, s3 and 35i.Elements 23, 29 and 3l? correspond to the counter 9 of block diagram 2.Element Si corresponds to counter ii of block diagram 2. Elements Si?and 33 correspond to counter l of block diagram Element 3Q correspondsto counter i3 of bloot: diagram 2. The circuit combination representedby each of the blocks 28, 2t, se, s2, it and Se are all identical andare shown in detail in Fig. 5. The terminals of each o1 these elementscorrespond to the terminals in Fig. 5 having the same literaldesignations.

Referring now to Fig. 5, there is shown a circuit combination comprisinga electron olisw charge device 35, having a cathode 36, a grid 3l, andan anode 38, and a second electron discharge device 39 having a cathodeet?, grid ti, an anode $2. The cathocles 3Q and fr@ are connected to oneend of cathode bias resistor s3, the other end of which is connected toground. Resistor 43 is bypassed by capacitor lill. Grid 31 is connestedthrough grid resistance to ground. Grid 31 is also connectecl through aparallel combination of resistance 4@ and capacitance il to G2. Theanode 33 is connected through anode resistance 45! to the positiveterminal of the power supply. Anode 38 is also connected through acoupling resistance 13S and through coupling capacitor 50 to pulse inputterminal o. The anode 3S is further connected-t0 .iced-baci; terminal.e- The arid .4| is ccnnetedthrouah-crid .resistance 5i to ground. The.grid 4| is also connected through a parallel combination oi' resistance,52

and capacitance 53 to `anode 38. Grid 4| is vfurther connected to inputterminal d. The anode d2 is connected through anode resistance 54 to thepositive terminal of the power supply, Anode .42 is also connectedthrough a coupling resistance 5i to the common connection of capacitors49 and 58. Anode 42 is further connectedto output terminal c. Thepositive terminal of the power supply is terminal l).

The circuit combination described in the preceding paragraph is -reerredto in the artas a heavily biased relaxation oscillator with two stableconditions of operation, i. e., the current flowing through one ci theacove referred-to devices changes abruptly from one value to a vsecondvalue when the circuit combination is suitably triggered or actuated bya negative pulse applied at input terminal a. With regard to the manneror operation ci the aoove circuit combination, assume that device 39 isconducting. A

negative triggering pulse applied at terminal a is coupled to the griddi through resistance 52 and capacitance 59, and lowers the potential ofthis grid. The lowering of potential 0i grid di cause-s a reduction inconduction of device 39, thereby causing the anode potential o device 39to rise.

The negative pulse applied to terminal o. has no eilect on device 35,since grid 9'! of device 95 is already biased negatively hy the voltagedrop across cathode resistance 3. The `rise in potential at anodethrough the parallel. combination of? resistance de and capacitor El,causing the .devise to start conducting. The ci "rent conduction throughde vice causes a reduction in the potential at '.he afde anode causesgrid il to further drop in poe tential to further r @ce conduction indevice This positive .ach action `causes the device 99 to becomenonfconductive, and the device to he conductii e, in an ei-:treinelyrapid time. if now another negative triggering pulse is applied toterminal the reverse action would taire place, leaving d vicenen-conductive and device conductive..

Referring new again to Fig. 4, terminal a lof element 29 is connected tothe anode 55 of electron discharge device 59. Terminal b of element 28is connected to the positive terminal of the power supply.

Terminal c of device 23 is connected to terminal a or element 29,Terminal 'o of element '29 is connected to the positive terminal of thepower supply. Terminal c of element 29 is connected to the terminal a,of device 39. Terminal l; of element 39 is connected to the-posi tiveterminal of the power supply. Terminal c o element 39 is connectedthrough a series -networlr. comprising capacitance 5l and resistance 58,to terminal d of element 29. Elements 28, 29 and 99 together correspondto the block 9 of Fig. 2.

Terminal 99e is connected to grid Si! of electron discharge device iiithrough coupling capacitor 59. Device 6| includes cathode'EZ connectedto ground and anode 93 connected to the lpositive terminal of the powersupply through load resistance 84. The grid 59 is a-lso connected toground through grid resistance 65. The anode S3 is connected toterminals 32a and 3 la.

Eier ent 3| corresponds to block of Fig. 2.

Elements 32 and 33 correspond to block .|12 of 42 is applied to the gridre Aucticn o the potential at i.

AFig. .Element 34 corresponds to Yblock l|3 4of Fig. 2. Terminals 3|b,32h, 33h, 34h areconnected to the positive terminal of the power supply.Terminal l3io is connected through a parallel combination of resistance56 and capacitance 61 in series with a capacitance 68 to grid 69 ofelectron discharge device lll. Electron discharge device l0 includes acathode 1| connected to ground through resistance 12 and anode 13connected through anode load resistance 14 to the positive terminal ofthe power supply. The grid B9 is also connected through grid resistance'l5 to ground. Terminal 32e is connected to terminal 33a. Terminaltfe is,connected through a series network of capacitance 16 and resistance 1lto terminal 32e. Terminal 33e is connected to terminal 34a. Terminal 34ois connected through a parallel network `of resistance 18 andcapacitance 19 in series with coupling capacitor 80 to grid 3| ofelectron discharge device 82. Grid 8| is also connected through gridresistance 83 to ground. The anode 83 of electron discharge device 82 isconnected through anode load resistance 135, to the positive terminalor" the power supply. The cathode of electron discharge de vice 82 isconnected through cathode load resistance 89 to ground. Cathode 85 isalso connected through coupling capacitance 81 to grid 88 of device 39,and to control grid 90 of device 56. Device 5e is an electron dischargedevice having a cathode 9|, a grid 92, a screen grid 93, a secondcontrol grid 9|), and an anode 55. Cathode 9i is connected to ground.The grid 92 is connected to grid resistance 94 to ground. Grid 92 isalso connected through coupling capacitance 95 to terminal 3 on delayline I of Fig. 2. The screen grid 93 is connected to a positive point onthe power supply. The anode 55 is connected through anode loadresistance 96 to a positive point on the power supply. As'pointed outabove, anode 55 also is connected to terminal 28a. Amplier 55 functions`to supply the pulses from terminal 3 of the delay line to terminal 28a.Terminal 90 is also connected through resistance 91 to a negative pointon the power supply. In the absence of an actuating potential onelectrode 98 from device 82, the device 56 is nonconductive.Accordingly, in the absence of an unbiasing signal on grid 99, pulsesapplied at terminal 3 do not reach terminal 29a.

Device 98 in the upper right-hand corner of the drawing corresponds toblock I5 oi Fig. 2, and comprises cathode 99, grid |09, anode |0|.Cathode 99 is connected to ground. Grid |90 is connected through gridresistance |92 to a negative point on the power supply. Grid |99 is alsoconnected through capacitance |93 to terminal |03a to which may beapplied positive pulses corresponding to the leading edges of thevertical blanking signal. The anode |o| is connected through anode loadresistance |92 and inductance |93 lto the positive terminal of the powersupply. The anode |01 is connected through coupling `capacitor |94 toterminal 31d. Anode ||il is also connected through coupling capacitor|05 to terminal 34d.

.Referring now to the operation of the circuits described above, at thebeginning of the cycle of the counter chain comprising elements 28, 29,3|, 32, 33 and 34, the potentials at terminals 28o, 29o, 3|c, 32e, 33C,34C are at the lower of the two potentials that these terminals canassume and which corresponds to the two stable states of these elementsas pointed out in connection with the descrpition of Fig. 5. Thepotential at aecomo terminal 351e will be at the higher of the twopotentials this terminal can assume. The application of a positive pulsecorresponding to the leading edge of the vertical blanking signal toterminal H3311 initiates the cycle of operation of the counter chain.The positive pulse appearing at grid it causes a negative pulse toappear at the anode liii. This negative pulse is applied to terminals tld and 34d, causing terminals 3 ic and 3io to rise in potential. Therise in potential at terminal Sie is applied to decoupling networkcomprising capacitor 19, resistance i8 and capacitor 234i, causing arise in potential to appear at grid Si. The rise in potential at cathodeSii due to the rise in potential of grid 8| of device 32 is coupledthrough capacitance el to bias electrode Se of device et, causing deviceE56 to become conductive. The twice horizontal line scansion frequencypulses applied at terminal 3 are thus allowed to pass through the device56 and appear at terminal 28a.

With respect to the operation of elements 28, 29 and 3c, the negativepulse applied at terminal itc causes the potential at terminal 23e torise, as is readily apparent from a consideration of the explanation ofthe circuit combination of Fig. 5. The rise in potential at the terminal28o has no effect on element lil since element 29 is re sponsive only tonegative-going signals. Upon the application of a second pulse atterminal 28a potential at terminal 28e drops. This drop in potentialapplied to terminal 29u, causes the potential at terminal 2SC to rise.On the application of a third pulse to terminal 28a, the potential atterminal 28o again rises, but has no effect on element 2S. On theapplication of a fourth pulse to terminal 28a, the potential at terminal228e drops, thereby causing a drop in potential at terminal 29o. Thedrop in potential at terminal litio is applied to terminal 30a, causingthe potential at terminal 39e to drop. This drop in potential is appliedthrough delay network comprising resistance 58 and capacitance 5'! toterminal 2%, causing the potential at terminal 29o to rise again. Uponthe application of two more pulses to terminal 28a, the potential atterminal ille again falls, causing the potential at terminal tte torise. Thus, it is seen that the circuit arrangement comprising elements28, 29 and 3E) functions to develop at output terminal 30e a positivepulse for every six negative pulses applied to terminal 26a.

negative pulse appearing at terminal 30e is inverted by the device l,wherein it appears as a positive pulse at anode G3. Accordingly, thetrailing edge of this pulse is a negative-going edge which, 'whenapplied to terminal 3io., causes the terminal tic to fall in potential,as is apparent from a consideration of graph D of Fig. 3. Upon theoccurrence of sin more pulses at terminal 28a, the counter comprisingelements 28, 29, 36, again executes a complete cycle and causes thepotential at terminal 3io to rise as is apparent from graph D of Fig. Onthe occurrence of a third set oi six pulses at terminal 28a, the countercomprising elements llt, 29, 30 again executes a complete cycle, causingthe potential at terminal Sie to again fall, as shown in graph D. Thelagging edges of the three pulses appearing at the anode '53 due to theapplication of eighteen pulses to terminal causes the counter comprisingelements 32 and 33 to execute a complete cycle, causing the terminal 33oto rise in potential on the occurrence of the twelfth pulse in theseries of eighteen pulses and then fall in potential after the end ofthe eighteenth pulse in a mode of operation similar to the mode ofoperation of the counter comprising elements 28, 29 and 3i). The fall inpotential o point 33e is applied to terminal. 34a and causes thepotential of point 3A0 to fall, as shown in graph E of Fig. 3. It willbe recalled that at the start oi the cycle of operation of the counterchain, the potential of terminal 34o rose and now at the occurrence ofthe eighteenth pulse, the potential at this point dropped, therebyproducing a positive pulse which when applied to control electrode SEIof device 56 renders amplier 55 non-conductive and blocks the passage ofpulses from terminal 3 to terminal lila until the next cycle initiatedby application ci' a pulse at terminal w3c.

Since A.C. coupling is used from terminal 34o to control electrode et ofdevice 56, and since it is essential that a particular conductivecondition at terminal Mic coincide with the unbiasing of amplifier 5E,i. e., in order to insure that the apparatus starts in step, a pulse issupplied to terminal 34d to cause element St to assume a particularconductive state, so that when the negative pulse corresponding to theleading edge of the vertical blanking signal is applied to terminalBild, the change in potential at terminal :isc applied to grid 9Gthrough cathode follower 52 unblocks device 55E. Thus in the subsequentoperation of the counterchain, whenever terminal talc is at itspositive, or at the higher in potential of its two conductiveconditions, amplifier 5S is unblocked. To this end is provided electrondischarge device Hit having a. cathode lill', a grid ist, and an anodeitil. The cathode is oonnected to ground through resistance ll. Thecathode is also connected to the positive pole of the unilaterallyconducting device l i l. The negative pole of the unilaterallyconducting device is connected to terminal 34d. The grid its isconnected through resistance H2 to ground. The grid is also connectedthrough coupling capacitor H3 to terminal lili, to which may be appliedpositive signals corresponding to the trailing edge of the verticalhlanking signal. The anode it?) is connected to the positive terminal ofthe power supply.

Terminal 34d is at a higher potential than cathode i'l of device itil inthe absence of an applied positive signal to device iet. Accordnglyunilateral conducting device l il functions to disconnect terminal Stdfrom cathode iii? eX- cept during the application of a positive pulse togrid Hi8. The application oi a positive pulse to grid H38 causes thepotential of cathode lill' to rise a'bove the potential of terminal @lidthereby actuating element 34d to change from one conductive state toanother.

The positive pulses applied at terminal i ill may have the sameperiodicity as the vertical blanking signal and may be derived from thetrailing edges thereof.

Output terminal IIZa on which appears a signal of the kind shown ingraph D of Fig. 3 is connected to cathode 'H of device le andcorresponds to terminal H2@ of amplifier 22 of Fig. 2.

The anode 'i3 of device 'lli is connected through coupling capacitor IISto control grid lili of device 89 which also includes cathode l l5,screen grid Il, a second control grid 38 and an anode lll. Grid H5 isconnected through grid resistance H8 to ground. Cathode 89 is connectedto ground. Screen grid H5 is connected to a positive point on the powersupply. Control grid 88 is connected to cathode 85 of device 82 throughaceogeio l1 capacitor 81. Anode iii' is connected through anoderesistance lid to a positive point on the power supply. Anode isconnected through coupling capacitor |2t` to grid |2| of device |22which also includes cathode |23 and anode IN. Grid |2| is also connectedthrough grid resistance |25 to ground. Cathode |23 is connected toground. Anode |24 is connected through anode resistance |26 to apositive point on-the power supply. Since a signal of the form shown ingraph D of Fig. 3 1put reversed in polarity appears on grid id and asignal of the form shown in graph E of Fig. 3 appears on control grid88, a signal of the form shown in graph F of Fig. 3 but reversed inpolarity appears at anode |I1. This pulse applied to inverter device |22develops a Signal of the form shown in graph F of Fig. 3 at anode |24 oidevice |22. Output terminal' |21 is connected to anode |24 andcorresponds toterminal |21 of amplifier 25 of Fig. 2.

Output terminal |28 on which appears a signal of the form shown in graphE of Fig. 3 but reversed in polarity is connected to anode 83 of device82 and corresponds to terminal |28 of amplier 24 of Fig. 2.

While We have shown a particular embodiment of our invention, it will ofcourse be understood that we do not wish to 'ce limited thereto sincemany modifications, both in the circuit arrangement and in theinstrumentalities employed, may

be made, and we therefore, contemplate by the appended claims to coverany such modifications as fall within the true spirit and scope of ourinvention.

What we claim as new and desire to secure by i Letters Patent of theUnited States is:

l. Apparatus for developing groups of signals of accurately controlledoccurrence with respect to one another and of accurately controlleddurations, comprising a first counter means having an input circuit andan output circuit and arranged to develop a single impulse in saidoutput circuit for a predetermined number of impulses supplied to saidinput circuit, a second counter means having an input circuit and anoutput circuit, current conduction in the output circuit of said secondcounter means being changeable from one value to another upon theapplication of an impulse to its input circuit, the input circuit ofsaid second counter means connected to the output circuit of said rstcounter means, a third counter means having an input circuit and anoutput circuit and arranged to develop a single impulse in said outputcircuit for a predetermined number of impulses supplied to said inputcircuit, the input circuit of said third counter means connected to theoutput circuit of said rst counter means, a fourth counter means havingan input circuit and an output circuit, current conduction in the outputcircuit of said fourth counter means being changeable from one value toanother upon thev application of an impulse to its input circuit, theinput circuit of said fourth counterv means connected to the outputcircuit of said third counter means, switching means having an inputcircuit connected to a source of recurring series ofv electrical pulsesof short duration and an output circuit connected to the input circuitof said first counter means and a control circuit connected to theoutput circuit of said fourth counter means for allowing the passage ofsaid series of electrical pulses to said iirst counter means during theoccurrence of a particular conductive state in the output circuit ofsaid fourth counter means,

means for supplying a second series ofV pulses having a lower frequencythan said nrst-menhaving a frequency of occurrence determined byy theYfrequency of occurrence of the pulses of said second series of pulses,the duration of a pulse or the group appearing in the output circuit cithe second counter means being determined by the tim'erequired for theyiirst counter means yto execute a complete cycle, the duration of apulse of the group appearing iny the output circuit of the fourthcounter means being determined by the product of the time required forthe rst counter means to execute a complete cycle by the time requiredfor the third counter means to execute a complete cycle.

2; Apparatus for developing groups of signals of accurately controlledoccurrence with respect to one another and of accurately controlledduration comprising a first counter means having an input circuit and anoutput circuit and arranged to develop a single impulse in said outputcircuit for a predetermined number of impulses supplied to said inputcircuit, a second counter means having an input circuit and an outputcircuit, current conduction in the output circuit of said second countermeans being changeable from one value to another upon the application ofan impulse to its input circuit, the input circuit of said secondcounter means connected to the output circuit of said first countermeans, a third counter means having an input circuit and an outputcircuit and arranged to develop a single impulse in said output circuitfor a predetermined number of impulses supplied to said input circuit,the input circuit of said third counter means connected to the outputcircuit of said iirst counter means, a fourth counter means having aninput circuit and an output circuit, current conduction in the outputcircuit of `said fourth counter meansbeing changeable from one value toanother on the application of an impulse to its input circuit, the inputcir-l cuit of said fourth counter means connected to the output circuitof said third counter means, a` fifth counter means having an inputcircuit and an output circuit and arranged to develop a single impulsein its output circuit for a predetermined number of impulses supplied toits input circuit, the input circuit of said fifth counter meansconnected to the output circuit of said fourth counter means, a sixthcounter means having an input circuit and an output circuit, currentconduction in the output circuit of said sixth counter means beingchangeable from one value to another on the application of an impulse toits input circuit, the input circuit of said sixth counter meansconnected to the output circuit of said iifth counter means, switchingmeans having an input circuit connected to a vsource of recurringelectrical pulses of short duration and an output circuit connected tothe input circuitV of said first counter means and a control circuitconnected to the output circuit of said sixth means for allowing thepassage of said vseries 'of electrical pulses to said nrst counter meansduring the occurrence of a particular conductive state in the outputcircuit of vsaid sixth counter means, means for supplying a secondseries of pulses having a lower frequency than said Erst-mentionedseries of pulses to the input circuits of said second, fourth and sixthcounter means whereby groups of pulses are developed in the outputcircuits of said second, fourth and sixth counter means having afrequency of occurrence determined by the frequency of occurrence of thepulses of said second series, and having durations dependent on thetimes required for the first, third and fifth counter means to executecomplete cycles.

3. Apparatus for developing groups of signals of accurately controlledoccurrence with respect to one another and of accurately controlleddurations comprising a iirst counter .means having an input circuit andan output circuit and arranged to develop a single impulse in saidoutput circuit for a predetermined nuinher of impulses supplied to saidinput circuit, a second counter means having an input circuit and anoutput circuit, current conduction in the output circuit of said secondcounter means being changeahle from one value to another upon theapplication of an impulse to its input circuit, the input circuit ofsaid second counter means con- Lected to the output circuit of said :rstcounter means through an aniplier, a third counter means having an inputcircuit and an output circuit, and arranged to develop a single impulsein. said output circuit for a predetermined number of impulses suppliedto said input circuit, the input circuit of said third counter' nieanscon nested to the output circuit of said amplifier, a fourth countermeans having an input circuit and an output circuit, current conductionin the output circuit of said fourth counter means being changeable fromone value to another upon the application of an impulse to its inputcircuit, the input circuit of said fourth counter ineans connected tothe output circuit of said third counter means, an amplifier meanshaving an input circuit connected to a source of recurring series ofelectrical pulses of short duration and an output circuit connected tothe input circuit of said rst counter means and having a control circuitconnected. to the output circuit of a third amplier, the input circuitof s aid third. amplifier connected to the output circuit of said fourthcounter means for allowing the passage of a series of electrical pulsesto said first counter means during the occurrence of a particularconductive state in the output circuit of said fourth counter means,means for supplying a second series of pulses having a lower frequencythan said first-mentioned seri-es of pulses to said second and fourthcounter means, whereby groups of pulses are developed in the outputcircuits of said second and fourth counter means, having a frequency ofoccurrence determined by the frequency of occurrence of the pulses ofsaid second series and having a duration dependent on the time requiredfor the first and third counter means to execute complete cycles.

4. Apparatus for developing groups of signals of accurately controlledoccurrence with respect to one another and of accurately controlleddurations comprising a first counter means having an input circuit andan output circuit and arranged to develop a single impulse in saidoutput circuit for a predetermined number of irnpulses supplied to saidinput circuit, a second counter nieans having an input circuit and anoutput circuit, current conduction in the output circuit of said secondcounter means being changeable freni one value to another upon theapplication of an impulse to its input circuit, the input circuit ofsaid second counter means connected to the output circuit of said firstcounter Cil la means through an amplifier, a third counter means havingan input circuit and an output circuit, and arranged to develop a singleimpulse in said output circuit for a predetermined nun per of impulsessupplied to input circuit, thc input circuit of said third counter meansconnected to the output circuit of said amplifier, a fourth counterzneans having an input circuit and an output circuit, current conductionin the output circuit of said fourth counter means being changeablefroin one value to another upon .the application of an impulse to itsinput circuit, the input circuit of said fourth counter means connectedto the output circuit of said third counter means, an amplifier meanshaving an input circuit connected to a source of recurring series ofelectrical pulses of short duration and an output circuit connected tothe input circuit of said first counter ineenl and having a controlcircuit connected to the output circuit of a third ampliner, the inputcircuit of said third amplifier connected to the output circuit of saidfourth counter means for allowing the passage of series of electricalpulses to said iirst counter means during the occurrence of a particularconductive state in the output circuit of said fourth counter means,neans for supplying a pulse to the input circuit of said fourth counterrneans prior to the first cycle of operation of said fourth countermeans whereby the cycle of operation of said fourth counter .cleansalways starts from the saine particular conductive state of the outputcircuit of said fourth counter means, means for supplying second seriesof pulses having a lower frequency than said first-mentioned series ofpulses to said second and fourth counter means, whereby groups of pulsesare developed the output circuits of said second and fourth counter'means, having a frequency of occurrence determined hy the frequency ofoccurrence of the pulses of said second series and having a durationdependent on the time required for the first and counter means toexecute complete cycles.

5. In a television system, apparatus for developing groups of signals ofaccurately controlled occurrence with respect to one another and ofaccurately controlled durations comprising a first counter means havingan input circuit and an output circuit and arranged to develop a singlepulse in said output circuit for every six pulses supplied to said inputcircuit, a second counter means having an input circuit and an outputcircuit, current conduction in the output circuit of said secondcontourmeansheing changeable from one value to another upon theapplication of a pulse to its input circuit, the input circuit of saidsecond counter means connected to the output circuit of said Erstcounter means through an amplier, a third counter means having an inputcircuit and an output circuit, and arranged to develop a single pulsefor every three pulses supplied to said input circuit, the input circuitof said third counter means connected to the output circuit of saidamplifier, a fourth counter means having an input circuit and an outputcircuit, current conduction in the output circuit of said fourthcontourrneans being changeable from one value to another upon theapplication of a pulse to its input circuit, the input circuit of saidfourth counter means connected to the output circuit of said thirdcounter means,

twice horizontal line scansion frequency of' said television system andan output circuit con-Y nected to the input circuit of said iirstcountermeans and having a control circuit connected to the output circuit of athird amplifier, the input circuit of said third amplier connected tothe output circuit of said fourth counter means for allowing the passageof said electrical pulses to said first counter means during theoccurrence of a particular conductive state in the output circuit ofsaid fourth counter means, means for supplying a second series of pulseshaving aV lower frequency than said nist-mentioned series of pulses tosaid second and fourth counter mea-ns, whereby groups of pulses aredevelopedin the output circuits of said second and fourth counter means,having a frequency of 'occurrence determined by the frequency ofoccurrence of the pulses of said second series and having a durationdependent on the time required for the first and third counter means toexecute complete cycles.

6. In combination, in a system for developing two groups or pulses, thepulses of one group occurring in accurately timed relationship withrespect to the pulses of the other of said groups and the pulses of eachgroup having predetermined durations, two sources of recurrent pulses,the pulses of one of said sources having a substantially higherfrequency than the'pulses of the other of said sources, means responsiveto the occurrence of said low frequency pulses and to the occurrence ofsaid high frequency pulses which occur after each of said low frequencypulses for developing impulses, each impulse occurring after theoccurrence of a predetermined number of said high frequency pulses,means responsive o said low frequency pulses and to said impulses fordeveloping a group of recurrent pulses, each of said recurrent pulsesincluding a pulse having an occurrence during the time between a. lowfrequency pulse and a succeeding impulse and also including pulsesoccurring during the time between successive pairs of im* pulses aftersaid succeeding impulse, means responsive to said impulses fordeveloping a sec ond group of impulses, each of the impulses of saidsecond group occurring after a predetermined number of impulses of saidiirst group, each of said impulses of said second group occurring priorto the occurrence of the respective ones of said low frequency pulsesnext succeeding the respective ones initiating said impulses, meansresponsive to each ofthe impulses of said second group for renderingsaid first means non-responsive to said high frequency pulses, meansresponsive to said low frequency pulses and to said second group ofimpulses for developing a second group of pulses, each of said pulseshaving an occurrence from the time of occurrence of a low frequencypulse and a. succeeding one of said impulses of said control group.

'7. In combination, in a system for developing groups of pulses, thepulses ofy one group occurring in accurately timed relationship withrespect to. the pulses of the other of groups and the pulses of eachgroup having predetermined durations, two sources oi recurrent pulses,the pulses of one of said sources having a substantially higherfrequency than the pulses of the other of said sources, means responsiveto the occurrence of said low frequency pulses and to the occurrence ofsaid high frequency pulses which occur after each of said lov/ frequencypulses for developing impulses, each impulse occurring after theoccurrence of a predeter mined number of said high frequency pulses,means responsive to said low frequency pulses and to said impulses fordeveloping a group of recurrent pulses, each of said recurrent pulsesincluding a pulse having an occurence during the time between a lowfrequency pulse and a succeeding impulse and also including pulsesoccurring during the time between successive pairs of impulses aftersaid succeeding impulse, means responsive to said impulses fordeveloping a second group of impulses, each of the impulses of saidsecond group occurring after three of the impulses of said first group,each of said impulses of said second group occurring prior to theoccurrence of the respective ones of said low frequency pulses nextsucceeding the respective ones initiating said impulses, meansresponsive to each of the impulses of said second group forrenderingsaid first means non-responsive to said high frequency pulses,means responsive to said low frequency pulses and to said` second groupof impulses for developing a second group of pulses, each of said pulseshaving an occur rence from the time of occurrence of a low requencypulse and a succeeding one of said impulses of said second group, meansfor combining said first and second group of pulses to derive a thirdgroup of pulses, each pulse of which occurs during the time betweenoccurrence of the first and second impulse of first group of impulses.

CALVIN L. ELLES. RALPH W. ELSNER.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 2,286,450 White June 16, 1942 2,350,536 Schlesinger June 6,1944 2,468,256 Espley Apr. 26, 1949 2,515,613 Schoenfeld July 18, 19502,516,972 Bannaway Aug. l, 1950 2,556,933 Mulligan June l2, 19512570,775 DeBaun Oct, 9, 1951

